Electric heater



Nov. 30., 1926.

' J. E. sEDl-:RHoLM ELECTRIC HEATER Filed August 4, 1924 3 Sheets-Sheet 1 Nov. 30,1926. 1,609,132

l J. E. sEDERHoLM v ELECTRIC HEATER 3 Sheets-Sheet 2 '..Z'nverzfor' Nov. 30 ,1926.

ELECTRC HEATER 3 Sheets-Sheet 5 Filed August 4. 1924 f7 5"/ 54:, Q A MIL- n il: h, 3 55 I 45 46 Invenor AJzfzff er'zoZm Pate-ated Nov. 3o, 1926.

UNITED STATES 1,609,132 PATENT OFFICE.

JOHN E. SEDERHOLM, OF ST. PAUL, MINNESOTA, ASSIGNOR TO AMERICAN HOIST & IDEIBRICIK COMPANY, .A PARTNERSHIP COMPOSED OF F. J. JOHNSON .AND W. O. 'WASHBURN, OF RAMSEY COUNTY, MINNESOTA.

ELECTRIC HEATER.

Application lcd August 4, 192A. Serial No.r 730,091.

v This invention relates to improvements in electric` heaters particularly adapted for heating, for expansion purposes, metallic rings or bands, and the like, and more particularly relates to such an apparatusadapted to heat and expand steel tires to be shrunk onto Wheels, such for instance as the -drive wheels of a locomotive, or for heating steel ringsto beA shrunk onto a castiron wheel or disk to be used as a gear Wheel, in which case the teeth are cut in the steel ring thus shrunk on, to obtain maximum strength with a minimum of weight. y

Devices of this type employed at present for heating rings and bands to a predetermined degree so that they may be shrunk onto a' complementary member, usually employ a tank which is filled with a suitable heating medium, such as oil. This oil 1s heated' to a predetermined degree, usually by means of an loil or gas furnace, after which the articles to be heated and expanded are submerged therein. As soon as the ring or other article has been heated to the desired degree itis-removed from the tank by such means as a tackle-block orv small hoist. This type of furnace requires considerable space when properly installed, as it is usually necessary that it be built in a separate Well-ventilated room, to prevent the dangerous fumes emanating therefrom from being discharged .into the building and thereby impairing the health of attendants or workmen laboring thereabout. The

A above type of furnace is also objectionable in that it has been the source ,of serious damage to property .as a result of explosions and lires caused bythe accidental igniting of the combustiblemateriah such as oil and gas; used in its operation.

As hereinbefore stated, the novels-heater featurein this invention is of the electric g type. Generally, it consists of a U-shaped stationary iron core having a complemen-4 tary movable core arranged thereover adapted to engage the upper faces of the vertical legs thereof. One or more coils'or windings v are mounted. to encircle one of the upright -1 'legsof -the stationary core, and when this winding. is energized'by the How of electric '"curreiitf therethrough, lan electromagnetic circuit built up inlthe closed iron core, wlchin turn willinduce in the ring or other device, having a portion thereofl positioned between the upright legs of the stationary core, a current of very low potential but of very high amperage, thereby causing such device to rapidly heat, caused by the highresistance offered to the flow of current therethrou h. l

The object of this invention therefore is to provide an improved electric heater of simple and inexpensive construction, which will be safe and eflcient in 'operation and performance. v

Other objects of the invention will more fully appear from the following description and the accompanying drawings and will be Ipointed out in the annexed claims.

n the drawings there has been disclosed a structure designed to carry out the various objects of the invention but it is to be understood that the invention is n'ot confined to the exact features shown as various changes may be made Within the scope of theclaims which follow.

In the accompanying drawings forming a part of this specication,

Figure 1 is a vertical sectional view on lthe line 1-1 of Figure 2 of my improved dotted lines a ring posicircling one of the upright legs of the stationary core;

Figure 3 1s a sectional plan on the linev 3-3 of Figure 2;

Figure 4 is a wiring diagram of the device showing three diEerent heats;c

Figure' 5 is a modified construction shovin-v ing a side elevation of a portable type of heater, the movable core being shown in raised inoperative position; and v -Figure 6 is a plan view of Fio'ure 5.

l In the selected embodiment of the invention here shown there is illustrated an electric heater liaving a frame comprising opposed channel b ars 11 and 1 2 and a beam 13 aving an uprlght supporting member 14 secured to the rear end thereof adapted to support a horizontal beam 15 adapted to provide a track and to support a movablev other end thereof secured horlzontal beam 15 when the core 1s moved 1, the

to and from a complementary core 21, which will subsequently be described. The carriage 19 is preferably provided with a lever handle 22, and is so constructed that when positioned as shown in full lines in Figure core 16 will be elevated from the position shown in dotted lines in the same figure wherein the core 16 is shown lowered to contact with the upper portion of thestationary core 21. I

The stationary cor'e 21 vis arranged between the frame members 11 and 12 and is preferably secured thereto by means of tiebolts 23 and 24 which are suitably insulated from the laminated core 21. The stationary core 21 is substantially U-shaped in form, comprising a main body 21 and the upright legs 25 and 26 so that when the movable core 16 is moved into contact with theupper" faces of the upright legs 25 and 26 it will present an angular frame or structure as particularly shown in Figure 2. VThe iron Cores 16 and 21 are of usual construction, be-

ing built up of a plurality of sheet-iron lam-.`

inations suitably secured together7 as is common practice and well-known in the art.

The means provided for inducing an electro-magnetic circuit in the iron core when positioned as shown in Figure 2, preferably consists in the provision of a plurality of suitable coils or windings 27 arranged to encircle one of the upright legs of the stationary core 21. In the drawings I have shown the coils 27 mounted upon the upright leg 26, but it is to be understood, of course, that they may be mounted upon the opposed leg 25 with equal results. The coils 27 are suitably insulated and are preferably separated from one another by means of plates 28 of a suitable insulating material. These lnsulated plates 28 are preferably fitted to the walls of the upright leg 26 and are adapted to outwardly project beyond the outer' surfaces of the coils 27, thereby to loffer a protection of the coils against injury.

These insulated plates 28 also prevent the.

windings of the coils 27 from contacting with one another which might cause shortcircuiting and burning out of the coils. A pair of upright angle bars 29 are mounted at one end of the coils adjacent the upright leg 25. These angle bars 29 are preferably secured to the opposed channel-bars 11 and 12 of the main frame of the heater by such means as welding. A plate Stof suitable insulating material is arranged between the upright 'angle bars 29 in such a manner as to abut against the edges of kthe ihorizontal spacing plates 28 as particularly shown in Figure 2, thereby protecting the coils from injury which might be caused by the ring or other device to be heated coming lin con- -sage of the current,

tact therewith. An insulating plate 32 is positioned between the upright leg 25 and theVcoil-protecting plate 31 to prevent 'the article to be heated from coming in actual contact with'the lower horizontal portion of the core 21 when positioned thereon as shown in Figures 2 and 3.

In the operation of this novel ring heater, the movable core 16- is first removed from the upright legs 25 and 26 of the stationary core 21 as shown in Figure 1. Such removal of the core 16 from the stationary core 21 is effected by raising the handlever 22 from the position shown in dotted lines in Figure 1 to substantially a 'vertical position which will Icause the core 16 to be ele-v vated to the position shown in full lines in Figure 1. The carriage 19 may Lthenbe backwardly moved upon the horizontal beam 15, as shown in this figure, until the core 16 has been moved out of contact and away from the stationary core so as to permit a ring'or other device to be placed between or over the upright legs 25 and 26 of the stationary core, as shown; When the ring to be heated has been positioned upon the stationary core as shown in Figure 2, the movable core 16 will be returned to its operative position in contact with the upper faces of the upright legs 25 and 26 of the ,core 21 as shown in Figure 2. Electric current is then introduced in the coils 28 by the manipulation of a suitable switch, not shown. .As soon as current starts to iow in the'coils 27, an electro-magnetic circuit will be induced in the iron cores which forma complete circuit around one side of the coils 27 and around a portion of the ring to be heated, the electro-magnetic iluX thus induced in the iron cores 16 and 21 in turn inducing an electric a very low potential but a very high amperage. ring to carry this high ainperage, caused by the high resistance it offers to the pasthe friction caused by the current flowing through the ring becomes so great that the ring immediately4 begins to heat. As soon as the heat has reached a predetermined degree, the flow of current through the coils 27 will be interrupted lby means, of a suitable switch, and

current in the ring of f As a result of the inability of the `erated, or if desired, it may be controlled by means of a timed switch 4mechanism -which may be so adjusted as to automatically interrupt the flow of current through the coils 27 when a predetermined temperature has been reached in the heating of the rlng.

In the actual operation of this novel ring heater, it has'been found that the size or diameter of the ring or device to be heated has little to do with the time required to obtain a predetermined ring temperature. This heater, therefore, has proven of considerable advantage over present forms of heaters or furnaces used for this purpose` Its operation, and construction is very simple, thereby providing such a device which may be efficiently employed to heat, for expansion purposes, vmetallic rings to be shrunk onto such devices as locomotive drive wheels or large gear wheels.

If desired, the coils 27 may be connected up in such a manner that a number of different heats may be obtained in order that the ring or other device may be heated to different temperatures which is necessary, depending upon the material and diameter of the ring 1n order to obtain the proper expansion of the ring to provide a good shrink it. f

In Figure 4, there is shown a conventional,` Wiring diagram showing how the coils may be .connected in order to obtain such different heats. As here shown all of the coils 27 are connected in series but are so ar. ranged and tapped that the number of effective am ere turns thereof may be varied to obtain t e desired low of current through the coils 27. A conductor 34 leads from vone side of the main line, (not shown,) to

the upper coil 27 and a conductor 35 fromv the other side of the main line to a multiple switch mechanism comprising switches 36, 37 and 38. A wire 39 leads from the switch 36 to a tap 41 taken off the bottom of the second coil from the top, and a wire 42 :from the switch 37 to a tap 43 on the third coil, and similarly a wire 44 leads from the switch 38 to a tap 45 provided on the lower 'coil 27.-A By this arrangement it will be seen ,electrical connection with a suitable source .thatwhen the switch 36 is closed, the cur- "circuit is employed a higher temperature will be obtained lin the ring. When the switch 37 is closed, the current will flow through three of the coils 27 thus increasing the number of ampere turns in the circuit with thc result that less heat will .beobtaint-, and when the switch 38 is closed the four coils 27 will be connected in the circuit with an additional increase in the number of ampere turns, with the result that a lower heat or temperature will be obtained. The

form of multiple switch to be used is preferably of such construction that only one switch can, be closedat one time in order to revent short-circuiting and therefore burning out of the coils, which would result if two or more switches were closed at one time. Such a switch forms the subject matter of a pending application of the inventor hereof filed August 2, 1924, Serial #729,807.

' In Figures 5 and 6, there is shown a modified construction wherein the heater is portably mounted upon a small truck comprising the carrying wheels 46 and a frame 47 having handles 48 provided thereon whereby it may be conveniently transportedfrom place to place. Standards 49 arepreferably provided ont-he frame 47 to support the endl thereof when in operative position as shown in Figure 5. As here shown the stationary core 21 is relatively smaller in dimension than the one shown in Figures l, 2 and 3. The upper movable core 16 is pivotally mounted upon an upright supporting member 51 secured to the frame 47 in such a manner that it may be lowered to the position shown in dotted lines in Figure 1, wherein'jit is in contact witlrthe upper surfaces of the upright legs 25 and 26 of the stationary core. In this construction, there is shown but two coils 27, it being understood of course that any number may be used to accomplish the desired results. An insulated plate 52, preferably semi-circular in form, is mounted upon the stationary core 21 as shown in the drawings, andl this plate provides a support for the ring 53 when positioned on the heater as shown. The movable core 16 is preferably provided with a hand grip 54 whereby it may be raised from the dotted position yshown in Figure 5, to the full line position shown in this same figure. A loop or clevls 55 is also pivotally mounted thereon adapted to'v engage a hook 56 provided on an overhanging arm 57 to retain the core 16. in raised inoperative position. A sultable swltch box -58 is preferably mounted on the up- -right supporting member 51 which is in of electric energy and whereby the iiow of prising a pair of base-forming and claniping irons, holding therebetween the laminations of a U-shaped stationary core, said core providingrupright arms, and a workreceiving space therebetween, a coil lencircling one of the arms, a second pair of baseforming irons attached and extending laterally of one iron of the first pair, midway of the work space, a vertical iron secured between the second pair of irons, a trackiron connected at the t'op of the vertical iron, and extending forwardly and centrall over the work space, and -a movable core a apted to bridge the work space and rest upon the arms, and connections between said movable core and track for pendently4 disposing the core and for holding and guiding the same for lworking cooperation with the stationary core, whereby said movable core can be positioned tov permit the unobstructed removal of the work.

2. A device of the class described, comprising a pair of irons clampingly securing the laminations of a U-shaped core,said core providing vertical arms and a work-receiving space therebetween, coils encircling one of the arms, a second pair ot irons attached to the first pair midway of the work space, a vertical iron attached to the second pair of-irons, a horizontal iron as a trac at the top ofthe vertical iron and extending forwardly and centrallyl over the work space, amovable core adapted to bridge the work space and rest upon the arms, and connections between the movable core and trac'k for pendently disposing said movable core and guiding the same for placement upon the stationary core, and a stop on the track for engaging the connections to limit translative movement 'of the stationaryv core at a point vertically above said stationary core.

.vertical frame disposed rearwardly of the stationary core and providing a track overhanging said stationary core centrally of the work space, a movable core,'and connections between the same and the track disposing said core transversely of the track pendently therebeneath for movement in a direction at right angles to the faces of greatest area of the stationary core, said connections adapted to raise and obtain translation of the movable core to a point rearwardly of the stationary core, to permit unobstructed removal of the work.

4. An electric heater comprising a liframe, a core supported thereon and having legs spaced apart and adapted to receive the work to be heated het/Ween them, -a coil encircling one of said legs and having an electric circuit, an upright standard, a horizontal arm carried by said standard and over hanging said core, and a movable core slidably supported by said arm and adapted to be lowered to contact with said legs and form with said core a continuous metallic circuit and heating the work encircled by' 

